feat: Implement Clone for Box<dyn FilterPlugin>

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/filter_plugin/mod.rs

@@ -40,6 +40,12 @@ impl Clone for FilterChain {
     }
 }
 
+impl Clone for Box<dyn FilterPlugin> {
+    fn clone(&self) -> Self {
+        self.clone_box()
+    }
+}
+
 impl FilterChain {
     pub fn new() -> Self {
         Self {